Photoelectric no sheet trip device for a printing press



Feb. 16, 1965 R. G. FIELDING 3,159,476

PHOTOELECTRIC N0 SHEET TRIP DEVICE FOR A PRINTING PRESS Filed Nov. 30, 1962 5 Sheets-Sheet 1 Feb. 16, 1965 R. e. FlELDlNG PHOTOELECTRIC NO SHEET TRIP DEVICE FOR A PRINTING PRESS 5 Sheets-Sheet 2 Filed Nov. 30, 1962 FIG] Feb. 16, 1965 R. a FIELDING 3,169,475

PHOTOELECTRIC NO swam TRIP DEVICE FOR A PRINTING PRESS Filed Nov. 30, 1962 5 Sheets-Sheet 3 Feb. 16, 1965 R. G. FIELDlNG 3,169,476

PHOTOELECTRIC NO SHEET TRIP DEVICE FOR A PRINTING PRESS Filed Nov. 30, 1962 5 Sheets-Sheet 4 32 FlG.4c\ 5/ 50 4 52 FIG.4b

52 F|G.4d 1 50 46 FlG.4c

Feb. 16, 1965 R. G. FIELDING PHOTOELECTRIC NO SHEET TRIP DEVICE FOR A PRINTING PRESS Filed NOV. 30, 1962 5 Sheets-Sheet 5 F IG.8c

United States Patent 3,169,476 PHOTOELECTRIC N0 SHEET TRIP DEVICE FOR A PRINTING PRESS Raymond G. Fielding, Lymm, England, assignor to Linotype and Machinery Limited, London, England, a

British company Filed Nov. 30, 1962, Ser. No. 241,268 8 Claims. (Cl. 101-447) The present invention relates to a no sheet trip device for a printing press.

The invention is applicable to printing presses of the kind provided with swing grippers or like sheet transfer devices which move between the feed board and cylinder grippers or sheet conveyor grippers to transfer the sheet therebetween.

An object of the present invention is to provide a simple, reliable and comparatively inexpensive no sheet trip device in which the only moving part is a prism which can be easily and rigidly secured and is not easily damaged. The device calls for no moving electrical components and no electronic or electrical gates are required; the electrical system incorporated being composed of standard, Well tried components, ensuring reliable operation and ready availability.

'Accordingto the present invention a printing press of the kind defined is provided with a no sheet trip device comprising a light projector, a light receiver and a light reflector, the light reflector carried by the sheet transfer device and being so positioned that when the sheet transfer device is in the sheet take position and there is no sheet present, a light beam path is completed between the light projector and light receiver, the light receiver including a photocell, which when excited by the light beam gives an output suficient to energise means to trip the printing press.

The invention also includes a printing press of the kind defined provided with a no sheet trip device comprising a plurality of light projectors, the same number of light receivers and the same number of light reflectors, a light receiver and a light reflector being associated with each light projector, each light reflector carried by the sheet transfer device and so positioned that a light beam path is completed between a given light projector and its associated light receiver when the sheet transfer device is in the sheet take position and no sheet is present between that given light projector and its associated light reflector and light receiver, each light receiver including a trans ducer giving an electrical output sutiicient, when excited by the light beam, to actuate means to trip the printing press.

Also according to the present invention a printing 7 i present, the light beam exciting a photocell in the light receiver to give an output to energise means to trip the printing press. V

Included in the present invention is a printing press of the kind defined provided with a no sheet trip comprising a light projector positioned above the feed board of the printing press and in front of a light receiver, which light receiver is positioned adjacent the rear edge of the feed board, and a light reflector secured to the sheet transfer device for reflecting a light beam from the light projector to the light receiver when the sheet transfer device is in the sheet take position and no sheet is present, the light "ice beam exciting a photocell in the light receiver to give an output to energise means to trip the printing press;

Conveniently the light path is completed by means of one or more prisms secured to the swing gripper system of a printing press, whereby a beam of light, reflected by the prism, will, in the event of no sheet being present or failure of the swing grippers to grip a sheet, be beamed onto a photocell. The output from the photocell can be amplified and used to actuate a trip solenoid to stop the press.

In the following description the invention is shown applied to a two revolution flat bed printing press. Obviously the invention is also applicable to sheet fed rotary presses in which swing feeders, or some such equivalent sheet transfer device is employed.

The no sheet trip device according to the invention may, on sensing no sheet is present for feeding, actuate a relay to energise a solenoid actuating the known mechanical trip of the printing press, or the solenoid may open a switch in the printing press motor feed line stopping the printing press motor. Alternatively the no sheet trip device may actuate a relay energising a solenoid to actuate a valve or the mechanical linkage to prevent the impression cylinder coming on-impression.

In the brief description of printing press operation given below, the no sheet trip device is shown acting on the mechanism controlling the on-oif impression movements of the impression cylinder. It has not been considered necessary to describe or illustrate in detail the means for stopping the complete printing press since existing mechanical or electrical means can be utilised and readily adapted once the principles of the present invention have been understood.

The term, tripping the press, unless stated to the contrary, is to be understood as meaning actually stopping the printing press or holding the impression cylinder in an off impression condition.

Front of the printing press is to the right, FIGURE 1; Rear of the printing press is to the left, FIGURE 1.

In the accompanying drawings;

FIGURE 1 is a cross section of a swing gripper system, feed board, no sheet trip device and impression cylinder of a printing press.

FIGURE 1a is an enlarged detail view of one end of the feed board,

FIGURE 2 is a front elevational detail of the swing gripper system feed board and no sheet trip device,

FIGURE 3 is a side elevation of part of a printing press showing the control system for the impression cylinder,

FIGURES 4a to 42 are diagrams showing the swing grippers in various positions during an operational sheet feeding cycle.

FIGURE 5 is a cross section of an example of solenoid operated valve used for tripping the printing press,

FIGURE 6 is a schematic diagram of one arrangement of the no sheet trip device,

FIGURE 7 is a detail of one end of a feed board showing an infra-red filter positioned in front of a collimating lens for the no sheet trip device,

FIGURES 8a to 8c are perspective views of different prisms which can be used in the no sheet trip device, and,

FIGURE 9 is a detail of a modification of the arrangement shown in FIGURE 1.

Referring to FIGURE 3, the no sheet trip device is shown applied to a known type of two revolution fiat bed printing press. Since presses of this kind are Well known only a brief description of the press and its control system are considered necessary.

The impression cylinder 1 has each shaft end 2 supported in a bearing box 3 mounted in a guide 4 on the press frame 5. The box 3 is carried on the upper end of sion cylinder to come on-impression, that is, to cause a.

sheet held by grippers on the impression cylinder to be printed as the type bed passes beneath the cylinder.

The hydraulic jacks 18', on either side of the press, are actuated by means of a pump 11, driven from the press main drive, the pump receiving a supply of hydraulic fluid from a reservoir 12. A relief valve 13, having a manual adjustment 15, controls the impression load imposed by the hydraulic rams.

A main control valve 14 is operated in timed sequence with the press to produce operative strokes of the rams during the impression stroke in the press cycle.

Valve 14 acts as an exhaust valve, that is, when closed oil under pressure will actuate the hydraulic jacks 19; when the valve is open the impression cylinder 1 will rise under the action of the springs 7, and the oil will exhaust back to the reservoir 12.

A solenoid operated valve 2% is positioned between the valves 13 and 14, and when energised, the valve 29 will open so that the oil under pressure will exhaust back to the reservoir, thereby preventing any impression stroke of the impression cylinder taking place.

The solenoid valve 20, shown in FIGURE 5, has an inlet port 21 and two outlet ports 22, 23.

A valve plunger 24 has two portions 25, 26 of reduced diameter.

When a solenoid 27 is energised, as hereinafter described, the valve plunger 24 lifts in the valve casing, compressing a spring 28.

In the solenoid de-energised condition the plunger 24 is in the position shown in FIGURE 5, the portion 25 forming a communication between the inlet port 21 and outlet port 22 through the body of the valve. Thus oil under pressure can freely flow through the Valve to the hydraulic rams 1i), and the press can come on-off impression in its correct cycle under the control of the valve 14.

When the solenoid 27 is energised the plunger lifts and the portion 26 forms a communication between the inlet port 21 and outlet port 23, closing communication between the ports 21, 22. Thus oil under pressure is diverted back to the reservoir 12 and the printing press cannot come on impression.

The solenoid operated valve 20 is controlled by the no sheet trip device hereinafter described: the solenoid being energised when a sheet is not fed or is only half gripped by the sheet transfer device.

FIGURES 1 and 2 show a conventional swing gripper system for a two revolution flat bed printing press. Since the constructional details and operation of such a swing gripper system are well known, it is believed unnecessary to give a detailed description.

Extending between the side frames of the press and carried in bearings 30 is a swing gripper shaft 31. A number of spaced drop arms 32 (only one is shown in FIG- URES 1 and 2) are clamped to the shaft 31 and oscillate with the shaft, when that shaft is oscillated by mechanism, not shown, but well known in the art.

Each drop arm 32 carries in bearings, adjacent its lower end, two cross shafts 33, 34. The shaft 33 has a plurality of spaced sheet grippers 35 secured thereto and the shaft 34 has a plurality of abutments 36 secured thereto, there being one abutment for each sheet gripper and co-operating therewith so that a sheet, when suitably presented will be gripped between the gripper and its associated abutment.

Opening and closing of the sheet grippers 35 is effected by a cam 37 having a cam follower 38 following the contours of the cam and imparting motion to the shaft 33 through an arm 39, on which arm, at one end the cam follower 38 is mounted: the other .end of the arm 39 is secured to the shaft 33.

A spring 49 ensures resilient contact between the cam foilower 38 and cam 37.

A feed board 41 having front stops 42 pivotally mounted on ears 43, carried by the feed board, is positioned adjacent one end of the arc of travel of the swing gripper system. The front stops 42 are controlled by known means, not shown, whereby they will pivot downwardly when a sheet is to be fed from the feed board by the swing grippers.

The profile of the cam 37 is such that the grippers are opened as they approach the sheet take position adjacent the feed board 41 and then close onto a sheet. In known manner the cam 37 then makes a slight rotational movement so that as the grippers are swung back towards the impression cylinder 1 with the sheet the grippers will not open. The grippers open when the sheet has been swung from the feed board to the impression cylinder 1 and impression cylinder grippers 44 have closed on the sheet.

The swing grippers then complete their arc of travel, the cam 37 makes a slight rotational movement back to its original position, the grippers close and return towards thelfeed board in preparation for another sheet feeding cyc e.

In its simplest form the no-sheet trip device has a single light projector, prism and light receiver, and it is this simplest form which will now be described.

A cross shaft 45 extending between the press side frames 5 has adjustably mounted thereon a light tight lamp housing 46 containing a lamp 47.

A collimating lens tube 48 projects through the top of the housing 46 to project a pencil beam of collimated light from the lamp 47.

Secured by a bracket 49 to one of the drop arms 32 is a prism 50. As shown in FIGURE 1 this prism is of truncated wedge shape, which, in a given position will reflect the beam of light from the lens tube 48 along a path parallel to, but spaced from the light beam projected from the lens tube 48.

Although mirrors or other reflecting surfaces may be used in place of a prism, a prism is considered preferable as it is comparatively difiicult to damage.

A light receiver 51 is positioned below the feed board 41. The light receiver comprises a photocell 52 onto which light is beamed by a collimating lens tube 53. A hole 54 through the feed board 41 adjacent the rear edge allows passage of light through the feed board.

The electrical output from the photocell 52 is fed to an amplifier 55 actuating a relay 56, which, when actuated will effect energization of the solenoid 27 of the solenoid valve 20.

A cycle of sheet feeding is shown. diagrammatically in FIGURES 4a to 4d. In FIGURE 4e the conditions for a no sheet trip are shown.

Referring to FIGURES 4a to 4d. In FIGURE 4a a sheet 57 has just been fed to the cylinder grippers 44 and is being drawn off the feed'board 41 as the impression cylinder rotates. The front stops 42 have dropped to allow the sheet freely to pass.

A light beam 58 projected from the lens tube 48 hits the undersurface of the sheet and is scattered. Output from the photocell 52 is negligible, that is, it is too low to operate the relay 56.

In FIGURE 4b the swing gripper shaft 31 is swinging back to the sheet take position. Another sheet 57 is being fed down the feed board: the front stops 42 are up to catch the sheet at the end of the feed board.

The light beam 58 is now unobstructed by a sheet our shut/us r; tuna dorp sq], se 05 tnsrrd sq; SlQlUQ put: prism towards the feed board. Reflection of the light beam takes place and the beam emerges in a line parallel to that of entry, but nearer the impression cylinder. The photocell 52 is again unaffected.

In FIGURE 40 the sheet 57 has arrived at the front stops. The swing feed grippers then arrive at the sheet take position and close.

The light beam 53 is again reflected by the prism 50 to emerge from the prism, parallel to the entrant light beam, and directed at the hole 54- in the feed board. The sheet 57, however, covers the hole and the light beam is scattered so that, again, the photocell 52 is unaffected.

In FIGURE 4d the sheet 57 is shown about to be transferred from the swing grippers to the impression cylinder grippers. The light beam 58 is scattered by the sheet and the photocell 58 remains unaffected by this beam.

The swing gripper system then moves to the position shown in FIGURE 4a and a cycle of sheet feeding is completed.

FIGURE 42 shows the swing grippers in the sheet take position, but no sheet present at the front stops. The light beam 58 is reflected through the prism 50, through the hole 54 in the feed board, through the collimating lens tube 53 to the photocell 52. The output from the photocell is suflicient to actuate the relay 56 and hence energise the solenoid 27, preventing the impression cylinder coming on impression.

The relay 56 has self holding circuitry of any well known kind, not shown, so that the solenoid 27 is kept energised although the swing grippers make a feed movement. As the solenoid 27 is energised audible and/or visual warning is given, for example, by the warning light 63 lighting up. A reset button 69 can be pressed to reset the relay when the next sheet has been correctly placed and correct sheet feeding can again take place.

A cut out switch 61 is inserted in the leads from the relay 56 to the solenoid 27 so that the no sheet trip can be isolated if it is desired to run the printing press for any reason without passing sheets through and at the same time have the impression cylinder perform its cyclic on-ofi impression strokes.

Obviously, and as shown in dotted lines in FIGURE 3, in place of the relay 56 actuating the valve 20, the relay can be used to energise a solenoid operated switch 80 in the circuit of the motor 81 driving the printing press, so that on energisation the entire printing press will stop.

To prolong the life of the lamp 47 it may be run underpowered and a filter 62 inserted over the collimating lens tube 53, FIGURE 7, so that, for example, only infrared light will be passed to the photocell 52, which photocell is sensitive to such radiations.

In FIGURE 6 three optical sheet sensing units are shown. In such an arrangement each optical unit, that is light projector 46, prism 50, light receiver 51 and amplifier 55 is capable of actuating the relay 56 if a light beam is received by any one of the light receivers. Thus a twisted sheet will trip the press as well as the absence of a sheet. If narrow sheets are to be fed, one or more of the projectors 46 can be switched off, or the requisite holes 54 closed by shutters, not shown.

FIGURES 8a, 8b and 8c show diflerent forms of prism suitable for mounting on the drop arm 32. The prism 50, shown in FIGURE 8a is a truncated wedge shaped prism; the prism 70 shown in FIGURE 8b is an equisided triangular wedge prism.

The arrangement shown in FIGURE 80 comprises two right angled prisms 71, 72, the prism 72 having means to vary its distance from the other prism. The means comprise a prism backing plate 73 having a flange 74 projecting into a guide way 75 formed in a plate 76 to be secured to a drop arm 32. The flange 74 has a threaded bore passing through it to receive a threaded rod 77 which can be rotated but not moved axially by the knob 78. Rotation of the knob 78 will slide the flange, and hence the backing plate 73, along the guiding and therefore move the prism 72 towards or away from the prism 71.

By this means manufacturing or assembling inaccuracies can be accommodate to ensure that the light beam reaches the light receiver at the correctposition of the swing grippers.

In FIGURE 9 the light source 46 is mounted above the feed board and projects a light beam at, in the position shown in FIGURE 9, a right angle prism 79 reflecting the light towards the light receiver.

Although such an arrangement works perfectly well, the positioning of the light projector as shown in FIG- URE 1 is preferred as such positioning leaves the area above the feed board free for access for the press operator to set or adjust front and side lays, sheet feeding devices and the like, and to remove twisted or crumpled sheets.

What is claimed is:

1. In a sheet fed printing press, the combination of a feed board, a rotary cylinder, a gripper mechanism intermittently movable between a sheet take and a sheet delivery position for transferring sheets from said feed board to said rotary cylinder, means for arresting said gripper mechanism in the sheet take position, and a no sheet trip device comprising light projector means, light receiver means, reflector means mounted on said gripper mechanism to reflect a beam of light from said projector means to said receiver means when said gripper mechanism is in a sheet take position, said light beam following a path that is intersected by a sheet in delivery position on said feed board, and means responsive to reflection of the light beam to said receiver means in the absence of a sheet for tripping the printing press.

2. The combination according to claim 1 wherein said reflector means includes two prisms, and means for adjusting one prism relatively to the other prism.

3. In a sheet fed printing press, the combination of a feed board, a rotary cylinder, a gripper mechanism in termittently movable between a sheet take and a sheet delivery position for transferring sheets from said feed board to said rotary cylinder, means for arresting said gripper mechanism in the sheet take position, and a no sheet trip device comprising a plurality of light projector means, a plurality of light receiver means, a plurality of reflector means mounted on said gripper mechanism transversely to the direction in which said means moves in transferring a sheet to said rotary cylinder, each of which reflector means reflects a beam of light from a light projector means to an associated light receiver means when said gripper mechanism is in a sheet take position, each light beam following a path that is intersected by a sheet in delivery position on said feed board, and means responsive to reflection of any light beam to its associated light receiver for tripping the printing press.

4. The combination according to claim 3 wherein each of said reflector means includes two prisms, and means for adjusting one prism relatively to the other.

5. In a flat bed printing press, the combination of a feed board, a rotary cylinder, a gripper mechanism movable between a sheet take and a sheet delivery position for transferring sheets from said feed board to said rotary cylinder, means for oscillating said gripper mechanism between the sheet take and sheet delivery positions and for arresting said mechanism in the sheet take position, hydraulic means including an hydraulic ram, a pump for feeding fluid under pressure to said ram, and a control valve for periodically connecting said pump to said ram to reciprocate said rotary cylinder into and out of contact with the type bed, and a no sheet trip device comprising light projector means, light receiver means, light reflector means mounted on said gripper mechanism to reflect a beam of light from said projector means to said receiver means when said gripper mechanism is in a sheet take position, said light beam following a path that is intersected by a sheet in delivery position on said feed board, and a solenoid-actuated valve operated in response to reflection of the light beam to said receiver means in .the absence of a sheet to prevent fluid under pressure being fedto said hydraulic ram whereby said rotary cylinder is maintained out of contact with the typebed.

6. The combination according to claim 5 including electrical connections between said light receiver means and said solenoid-actuated valve, and means for interrupting .said electrical connections whereby the rotary cylinder can be reciprocated into and out of contact With the type bed without sheets being positioned for delivery on the feed board.

7. The combination according to claim 5 including sig nal means responsive to reflection of the light beam to said receiver means for indicating that a sheet is not in delivery position on the feed board.

8. The combination according to claim 5 wherein said light receiver means maintains said-solenoid valve operated after the light beam is interrupted by movement of Q 4.) means for interrupting the operation of the solenoid valve preparatory to a succeeding sheet delivery cycle.

References Cited by the Examiner UNITED STATES PATENTS 1,999,618 4/35 Raymond 197-127 2,072,236 3/37 Wormser 271-57 2,105,470 1/ 3 8 Bower.

2,416,595 2/47 Reynolds 271-57 X 2,543,848 3/51 Hanson 88-68 X 2,594,741 4/52 Dexter 192-127 X 2,818,252 12/57 Nilsson 27l57 2,963,293 12/60 Klein 27157 3,080,814 3/63 Rainford 101-283 FOREIGN PATENTS 365,341 1/ 32 Great Britain.

ROBERT E. PULFREY, Primary Examiner.

.the gripper mechanism out'of the sheet take position, and 20 EUGENE R. CAPOZIO, Examiner. 

1. IN A SHEET FED PRINTING PRESS, THE COMBINATION OF A FEED BOARD, A ROTARY CYLINDER, A GRIPPER MECHANISM INTERMITTENTLY MOVABLE BETWEEN A SHEET TAKE AND A SHEET DELIVERY POSITION FOR TRANSFERRING SHEETS FROM SAID FEED BOARD TO SAID ROTARY CYLINDER, MEANS FOR ARRESTING SAID GRIPPER MECHANISM IN THE SHEET TAKE POSITION, AND A NO SHEET TRIP DEVICE COMPRISING LIGHT PROJECTOR MEANS, LIGHT RECEIVER MEANS, REFLECTOR MEANS MOUNTED ON SAID GRIPPER MECHANISM TO REFLECT A BEAM OF LIGHT FROM SAID PROJECTOR MEANS TO SAID RECEIVER MEAN S WHEN SAID GRIPPER MECHANISM IS IN A SHEET TAKE POSITION, SAID LIGHT BEAM FOLLOWING A PATH THAT IS INTERSECTED BY A SHEET IN DELIVERY POSITION ON SAID FEED BOARD, AND MEANS RESPONSIVE TO REFLECTION OF THE LIGHT BEAM TO SAID RECEIVER MEANS IN THE ABSENCE OF A SHEET FOR TRIPPING THE PRINTING PRESS. 